Paper feeding device and image forming apparatus

Abstract

To provide a roll paper feeder for automatically performing a paper feeding operation after detection of a roll paper tip, which can prevent disabled detection of a sheet tip not peeled due to a curled state of a sheet, static electricity or the like at low cost.SOLUTION: A paper feeder 90 for feeding a sheet from roll paper Pr on which the long sheet is wound comprises: a sensor 93 with detection accuracy that can detect a step of a sheet tip on the surface of the roll paper Pr; a roller 92 disposed at a position different from that of the sensor 93 in the circumferential direction of the roll paper Pr; and a support member (arm 91) placed near the sensor 93 and the roller 92 and which can support them so as to abut against the surface of the roll paper Pr. The sensor 93 and the roller 92 are arranged toward a core of the roll paper, and a mechanism (e.g., pressure release solenoid 98) for generating a peripheral speed difference between the roller 92 and the roll paper Pr is provided.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a paper feeding device and an image forming apparatus.

Background Art

[0002] In an image forming apparatus using roll paper, a technique has been proposed in which the leading edge of the paper is automatically detected and then the paper feeding operation is performed without the user manually inserting the leading edge of the paper into the paper feeding and conveying unit (for example, Patent Document 1). However, due to the curling condition of the paper or static electricity, there are cases where the leading edge of the paper cannot be peeled off and separated. For example, in Patent Document 2, even for roll paper under severe conditions where the leading edge of the roll paper sticks to the roll paper, such as when the leading edge of the roll paper is strongly curled inward or when the roll paper itself is charged with static electricity, a roll paper separating mechanism capable of separating the leading edge of the roll paper is disclosed, but it is a costly configuration and there is room for improvement.

Summary of the Invention

Problems to be Solved by the Invention

[0003] An object of the present invention is to prevent, at a low cost, the leading edge of the paper from not being peeled off and the leading edge of the paper from not being separated due to the curling condition of the paper, static electricity, etc. in a roll paper feeding device that automatically performs a paper feeding operation after detecting the leading edge of the roll paper.

Means for Solving the Problems

[0004] In order to solve the above-described problems, the present invention is a paper feeding device that supplies the paper from a roll paper around which a long paper is wound, A motor that rotates the spool on which the aforementioned roll of paper is wound, a sensor having a detection accuracy capable of detecting a step at the leading edge of the paper on the surface of the roll paper, a roller disposed at a position different from the sensor in the circumferential direction of the roll paper, and a support member that disposes the sensor and the roller in the vicinity and can be supported so as to abut on the surface of the roll paper. The sensor and the roller are arranged toward the core of the roll paper, In order to separate the leading edge of the paper from the surface of the roll paper A mechanism is provided to create a peripheral speed difference between the roller and the roll paper. 、 The mechanism that generates the peripheral speed difference generates the peripheral speed difference by detecting the leading edge of the paper, stopping the rotation of the motor, suppressing the peripheral speed of the roller while the roll paper and the roller are in contact, and then rotating the motor to transport the roll paper in the paper feeding direction. It shall be considered as such. [Effects of the Invention]

[0005] According to the present invention, in a roll paper feeder that automatically feeds paper after detecting the leading edge of the roll paper, it is possible to prevent the leading edge of the paper from peeling off and being separated due to the curling of the paper, static electricity, etc., at low cost. [Brief explanation of the drawing]

[0006] [Figure 1] This is a perspective view of a schematic configuration example of an image forming apparatus according to an embodiment. [Figure 2] This is a side cross-sectional view of the image forming apparatus. [Figure 3] This is a side view illustrating the main components of an example configuration of a paper feed device according to an embodiment. [Figure 4] This is a diagram illustrating an example of an arm configuration. [Figure 5] This is a block diagram illustrating an example of the paper feeder's functions. [Figure 6] This diagram illustrates an example of how to detect unevenness on the surface of a roll of paper. [Figure 7] This diagram illustrates the positional relationship between the roller, the sensor, and the leading edge of the paper roll. [Figure 8] This diagram illustrates the changes in the sensor signal shown in Figure 8. [Figure 9] This diagram illustrates an example of a detailed change in the sensor signal. [Figure 10] This diagram illustrates another example of detailed changes in sensor signals. [Figure 11] This is a flowchart illustrating an example of the operation of setting a roll of paper into the paper feed device. [Figure 12] This is a flowchart illustrating an example of how to detect the tip. [Figure 13]It is a flowchart for explaining an operation example of detecting the tip again. [Figure 14] It is a diagram for explaining an example of a state in which the paper is loosened and the tip of the roll paper is separated from the surface of the roll paper. [Figure 15] It is a flowchart for explaining an operation example of setting the roll paper of Embodiment 1 in the paper feeding device. [Figure 16] It is a flowchart for explaining an operation example of setting the roll paper of Embodiment 2 in the paper feeding device. [Figure 17] It is a flowchart for explaining an operation example of setting the roll paper of Embodiment 3 in the paper feeding device.

Mode for Carrying Out the Invention

[0007] Hereinafter, embodiments of the present invention will be described based on the attached drawings. In each of the drawings for explaining the embodiments of the present invention, components such as members and components having the same function or shape are given the same reference numerals as much as possible so that the description can be omitted after being described once.

[0008] Referring to FIGS. 1 and 2, a configuration example of an image forming apparatus to which a paper feeding device according to an embodiment of the present invention is applied will be described. The paper feeding device supplies paper from a roll paper in which a long paper (also referred to as a "sheet") is wound in a roll shape. The image forming apparatus is an inkjet printer that prints on a recording medium by ejecting ink droplets corresponding to image data, but the present invention can also be applied to a copying machine or a printing machine such as an electrophotographic method that conveys a recording medium and performs printing.

[0009] FIG. 1 shows a perspective view of a schematic configuration example of an image forming apparatus 80 according to an embodiment, and FIG. 2 shows a side cross-sectional view of the image forming apparatus. The overall configuration of the image forming apparatus according to the embodiment and the operation of the main part will be described. The arrow in FIG. 1 indicates that X is the depth direction (front-rear direction) of the image forming apparatus 80, Y is the width direction (main scanning direction) of the image forming apparatus 80, and Z is the vertical direction.

[0010] In FIG. 1, the image forming apparatus 80 is an image forming apparatus of a serial type liquid ejection method (ink ejection method), and the main body housing 81 is disposed on the main body frame 82. In the image forming apparatus 80, a main guide rod 64 and a sub-guide rod 65 are stretched in the main scanning direction indicated by the double-headed arrow Y in FIG. 1 inside the main body housing 81. The main guide rod 64 supports the carriage 66 movably, and a connecting piece 66a that engages with the sub-guide rod 65 to stabilize the posture of the carriage 66 is provided on the carriage 66.

[0011] An endless belt-shaped timing belt 67 is disposed along the main guide rod 64 in the image forming apparatus 80, and the timing belt 67 is stretched between a driving pulley 68 and a driven pulley 69. The driving pulley 68 is rotationally driven by a main scanning motor 70, and the driven pulley 69 is disposed in a state of applying a predetermined tension to the timing belt 67. By being rotationally driven by the main scanning motor 70, the driving pulley 68 rotates and moves the timing belt 67 in the main scanning direction according to its rotational direction.

[0012] The carriage 66 is connected to the timing belt 67, and when the timing belt 67 is rotationally moved in the main scanning direction by the driving pulley 68, the carriage 66 reciprocates in the main scanning direction along the main guide rod 64.

[0013] In the image forming apparatus 80, a cartridge unit 71 and a maintenance mechanism unit 72 are detachably housed at an end position in the main scanning direction inside the main body housing 81. In the cartridge unit 71, cartridges 73 that store yellow (Y), magenta (M), cyan (C), and black (K) inks are interchangeably housed. Each cartridge in the cartridge unit 71 is connected to a recording head (not shown) of the corresponding color mounted on the carriage 66 by a pipe (not shown), and ink is supplied from the cartridge unit 71 to the recording heads of each color through the pipe.

[0014] The image forming apparatus 80 records an image on the paper P by moving the carriage 66 in the main scanning direction and ejecting ink onto the paper P, which is intermittently transported on the platen 74 (see Figure 2) in a sub-scanning direction (arrow X direction in Figure 1) perpendicular to the main scanning direction.

[0015] While the paper P is not limited to paper, and various types such as rolled film can be used, in the following explanation, for clarity, the paper being transported will be referred to as paper P, the rolled state of paper P will be referred to as roll paper Pr (Pa, Pb), and the core of the roll paper Pr (also called "spool" or "core tube") will be referred to as Ps.

[0016] As shown in Figure 2, the image forming apparatus 80 has a chamber 75 with a fan located below the platen 74. By driving the fan, the paper P being transported on the platen 74 is transported while in close contact with the platen 74.

[0017] The image forming apparatus 80 intermittently transports the paper P in the sub-scanning direction, and while the transport of the paper P in the sub-scanning direction is stopped, it moves the carriage 66 in the main scanning direction and ejects ink from the nozzle row of the recording head mounted on the carriage 66 onto the paper P on the platen 74 to form (record) an image on the roll-shaped paper P.

[0018] The maintenance mechanism 72 cleans the ejection surface of the recording head, performs capping, ejects excess ink, etc., to remove excess ink from the recording head and maintain the reliability of the recording head.

[0019] The image forming apparatus 80 has an encoder sheet (not shown) arranged parallel to the timing belt 67 and the main guide rod 64, extending at least over the range of movement of the carriage 66. An encoder sensor for reading the encoder sheet is attached to the carriage 66. The image forming apparatus 80 controls the movement of the carriage 66 in the main scanning direction by controlling the drive of the main scanning motor 70 based on the reading result of the encoder sheet by the encoder sensor.

[0020] Furthermore, reflective sensors (encoder sensors, paper leading edge detection sensors) mounted on the carriage 66 detect both ends of the paper P transported to the image forming unit 60, and at that time, the size of the paper P is detected from the main scanning direction position read by the paper leading edge detection sensor.

[0021] As shown in Figures 1 and 2, the image forming apparatus 80 has two spool bearing bases 5a and 5b provided on the main frame 82 that supports the main housing 81, in the vertical direction in Figures 1 and 2.

[0022] The paper (roll-shaped paper) P, pulled out from the leading edge of the roll paper Pr set on the spool bearing bases 5a and 5b, is transported in the transport path 9 by the transport roller pairs 6a and 6b, the resist roller 10, and the resist pressure roller 17, as shown by the arrows in Figure 2. The control unit 100 controls the drive unit 7 to rotate the transport roller pair 6a, 6b, the resist roller 10, the resist pressure roller 17, etc. Below the roll of paper Pr(Pa,Pb), there are paper roll holders 8a and 8b to prevent the roll of paper Pr from falling.

[0023] The paper P passes through a transport path 9 supported by media transport guide members 18a, 18b, etc., and is transported onto the platen 74 in the image forming unit 60. If an image is to be formed on both sides, the paper is inverted in the inversion unit 19.

[0024] In the image forming unit 60, an image is formed when a liquid recording head ejects droplets of each color onto the paper P corresponding to the image data. The forward transport discharge section of the paper P on which the image has been formed is provided with a cutter 76 that extends in the sub-scanning direction (paper width direction) and is used to cut the continuous paper P to a predetermined length.

[0025] To align the leading edge of the continuous paper P being transported, the cutter 76 is fixed to a wire or timing belt stretched between multiple pulleys (one of which is connected to a drive motor), and moves in the main scanning direction Y by the drive motor to cut the paper P to a predetermined length. The cut paper P is discharged to the discharge section. Although Figures 1 and 2 show an example configuration of an image forming apparatus in which roll paper Pa and Pb can be set on two spool bearing bases 5a and 5b, an image forming apparatus with only one spool bearing base may also be used. Furthermore, in the above explanation, the configurations corresponding to the two rolls of paper Pa and Pb were described using identifiers a and b (for example, spool bearing bases 5a and 5b), but from now on, identifiers a and b will not be used when they are not distinguished.

[0026] Next, a paper feeding device according to an embodiment of the present invention will be described. The paper feeding device is an image forming apparatus that uses roll paper, and automatically detects the leading edge of the paper and performs a paper feeding operation without the user manually inserting the leading edge of the paper into the paper feeding transport section. The device holds the roll paper so as to be rotatable with respect to the center of the roll paper, and a support member (guide plate) is equipped with a roll paper leading edge detection sensor and a roll paper receiving roller that are pressed against and in contact with the surface of the roll paper. The paper feeding device is characterized in that, after detecting the leading edge by rotating the roll paper in the opposite direction to the paper feeding transport direction, when the roll paper is rotated into the paper feeding transport section, the receiving roller is stopped (or held down) by a mechanism (such as a brake mechanism) that creates a peripheral speed difference between the roller and the roll paper, thereby separating the leading edge of the paper from the surface of the roll paper.

[0027] One embodiment of the paper feeding device according to the present invention is a paper feeding device that supplies paper from a roll of paper wound on a long sheet of paper, comprising: a sensor (sensor 93) having detection accuracy capable of detecting a step at the leading edge of the paper on the surface of the roll paper; a roller (roller 92) positioned at a different location from the sensor in the circumferential direction of the roll paper; and a support member (arm 91) positioned near the sensor and capable of supporting the roller so as to contact the surface of the roll paper, wherein the sensor and roller are positioned toward the core of the roll paper and a mechanism (for example, a pressure release solenoid 98) is provided to create a peripheral speed difference between the roller and the roll paper. (The part in parentheses corresponds to the configuration shown in Figure 3, which will be described later, as an example.)

[0028] In this way, in an image forming apparatus using roll paper, a paper feeder that automatically detects the leading edge of the paper and performs the paper feeding operation without the user manually inserting the leading edge of the paper into the paper feed transport section, can reliably separate the leading edge of the roll paper from the surface of the roll paper with a simple configuration, thereby providing a low-cost solution to prevent transport failures. In this specification, the term "leading edge of paper" is also referred to as the "leading edge of roll paper," and no distinction is made between them.

[0029] Figure 3 is a side view illustrating the main components of an example of the configuration of a paper feed device according to an embodiment. The paper feed device 90 comprises at least an arm 91, a roller 92, a sensor 93, and a transport roller pair 6. The paper feed device 90 may further include an inlet guide plate 95. In addition, Figure 3 shows a pressure release solenoid 98 as an example of a mechanism that creates a peripheral speed difference between the roller 92 and the roll paper Pr. The pressure release solenoid 98 will be described in Embodiment 2 below, but for example, in Embodiment 1, the paper feed device 90 may be configured without a pressure release solenoid 98. In Figure 3, the position of the roll paper Pr when the user has set it in the paper feeder 90 is shown by a dashed line. The roll paper Pr is held in a modular component (not shown) so as to be rotatable with respect to the center (axis) of the roll paper.

[0030] The arm (guide plate) 91, which serves as a support member for the roll paper Pr, is configured to rotate around a pivot center 911. The arm 91 is pressed in the direction of the roll paper by a spring or the like on one side of the pivot center 911. As a result, the arm 91 will remain in contact with the outer diameter of the roll paper even if the roll diameter (diameter of the roll paper Pr) changes. The white arrow indicates the direction of rotation of the arm 91. Furthermore, the arm 91 holds the roller 92 and sensor 93 on the other side of the pivot center. The roller 92 and sensor 93 are positioned to face approximately the center (core Ps) of the roll paper Pr, regardless of the roll diameter. The arm 91 also supports the roller 92 and sensor 93 in close proximity, so as to contact the surface of the roll paper Pr.

[0031] The roll paper Pr is (1) rotated in the winding direction by a reverse motion, and the tip detection operation is performed. After tip detection, (2) the tip is sent in the paper feed direction by a forward rotation motion and is transported into the machine by the transport roller pair 6 (transport section). The area indicated by the arrow between roller 92 and the entrance guide plate 95 shows the paper leading edge stopping position. The paper feeder 90 detects the leading edge of the roll paper Pr, continues to reverse, stops the leading edge of the paper at the leading edge stopping position, and then transitions to forward rotation (CCW) operation, entering a print paper feed standby state.

[0032] Next, we will explain an example of the configuration of an arm as a support member. Figure 4 illustrates an example of the arm configuration, with (A) being a perspective view illustrating an example of the arm 91, (B) being a schematic diagram showing the external appearance of the sensor 93, and (C) being a side view illustrating an example of the actuator and side plate that constitute the sensor 93. In the arm 91, the roller 92 is positioned on the upstream side (rotation center side) during reverse operation, and the sensor 93 is positioned on the downstream side.

[0033] Sensor 93 uses an encoder sensor in which a slit 932 is provided on the actuator 931, and has a detection accuracy that can detect the step (paper thickness) at the leading edge of the roll paper. Sensor 93 can detect a step equal to the paper thickness by having a resolution of, for example, 5 μm / pulse. Actuator 931 is positioned between two side plates 933 that constitute the sensor housing, and a shaft 934 is fitted into the bearing of the side plate 933, and rotates around the shaft 934. The sensor 93 has a light-emitting section and a light-receiving section (not shown), and detects the leading edge of the roll paper Pr by counting the number of times light passes through the slit 932 of the actuator 931 from the light-emitting section to the light-receiving section (by counting the number of signal waveforms).

[0034] In the configuration example shown in Figure 4, two rollers 92 are provided, and a sensor 93 is placed between the two rollers 92. The rollers 92 are positioned at different locations from the sensor 93 in the circumferential direction of the roll paper Pr, and the rollers 92 and sensor 93 are offset from each other in the circumferential direction.

[0035] Next, we will explain the control of the paper feeder's functions. Figure 5 is a block diagram illustrating an example of the paper feeder's functions. The control unit 110 controls the entire paper feeding device. Figure 5 shows an example of a functional block in which the control unit 110 controls the sensor 93, the first motor drive unit 120, the second motor drive unit 140, and the mechanism 170 that creates a peripheral speed difference between the roller and the roll paper (labeled "roller peripheral speed adjustment mechanism" in Figure 5), with other functional blocks omitted. The functions of the control unit 110 may also be configured to be executed by the control unit 100 (see Figure 2), which controls the entire image forming apparatus.

[0036] The control unit 110 includes, for example, a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), and the like. The CPU executes various programs and controls the entire image processing system based on arithmetic processing and control programs. RAM is a volatile storage medium for high-speed reading and writing of information, and it functions as a work area when the CPU executes programs. ROM is a read-only, non-volatile storage medium in which various programs and control programs are stored.

[0037] The first motor drive unit 120 drives the motor under the control of the control unit 110, thereby driving the roll paper drive unit 130. The roll paper drive unit 130 rotates the roll paper in either the forward or reverse direction. The roll paper drive unit 130 has a roll paper rotation motor 131. The roll paper rotation motor 131 rotates a spool on which a long sheet of paper is wound. The second motor drive unit 140 drives the motor under the control of the control unit 110, thereby driving the transport drive unit 150. The transport drive unit 150 has a transport motor 151 and drives the transport unit 160. The transport unit 160 is a transport means for transporting paper, and for example, has a pair of transport rollers 6.

[0038] The mechanism 170 that creates a peripheral speed difference between the roller and the roll paper has, for example, a function to suppress the peripheral speed of the roller. Suppressing the peripheral speed of the roller may also mean stopping the rotation of the roller. The mechanism 170 that creates a peripheral speed difference between the roller and the roll paper will be described later with reference to Figures 15 to 17.

[0039] Next, we will explain an example of an operation that detects the step (paper thickness) on the surface of the roll paper and determines it to be the leading edge of the roll paper. Figure 6 illustrates an example of the operation for detecting unevenness on the surface of a roll of paper. Figure 6 shows the process of the leading edge of the roll paper Pr passing through the roller 92 and the sensor 93, with (A) showing the state before the leading edge of the roll paper passes through the roller 92, (B) showing the state after the leading edge of the roll paper has passed through the roller 92 but before it passes through the sensor 93, and (C) showing the state after the leading edge of the roll paper has passed through the sensor 93. Sensor 93 and roller 92 are positioned in close proximity and offset from each other. Because roller 92 is upstream of sensor 93, roller 92 can hold down the leading edge of the roll paper until just before sensor 93 detects the leading edge of the roll paper (Figure 6(A)). In this way, sensor 93 can detect the step (paper thickness) on the surface of the roll paper while keeping the leading edge of the roll paper in close contact with the surface. As a result, the output (detection result) of sensor 93 does not become unstable due to the thickness, stiffness, or curl of the paper, and sensor 93 can reliably detect the leading edge of the roll paper Pr.

[0040] When the roll paper Pr reverses direction and the leading edge of the roll paper passes the roller 92, the arm 91 rises, causing the actuator of the sensor 93 to lower (Figure 6(B)). When the leading edge of the roll paper passes the sensor 93, the actuator of the sensor 93 rises (Figure 6(C)). Here, the statement that the roller 92 and the sensor 93 are positioned in close proximity means, for example, that they are positioned at a distance where the actuator of the sensor 93 lowers when the leading edge of the roll paper passes the roller 92.

[0041] In Figure 6, the roller 92 is positioned upstream of the sensor 93, but detection is possible even with the reversed configuration. However, positioning the roller 92 upstream of the sensor 93 allows for more reliable suppression of the paper roll's leading edge until just before detection. Furthermore, as shown in Figure 4, by providing two rollers 92 and placing a sensor 93 between the two rollers 92, it becomes possible to more reliably hold down the lifting of the leading edge of the roll paper than with a single roller 92. In addition, by positioning the rollers 92 and the sensor 93 offset in the circumferential direction, even if there are partial scratches or other defects, the proportion of the impact on both the roller and the sensor is reduced, resulting in a configuration that is less prone to false detection.

[0042] Next, I will explain tip detection. Figure 7 illustrates the positional relationship between the roller, the sensor, and the leading edge of the paper roll. Figure 8 illustrates the changes in the sensor signal. Figures 9 and 10 illustrate an example of detailed changes in the sensor signal.

[0043] The control unit 110 reverses the roll paper Pr using the first motor drive unit 120 (CW) and detects the leading edge of the roll paper by detecting the signal slope (K1) when the leading edge of the roll paper passes the roller 92 (timing t1 in Figure 7) and the signal slope (K2) when the leading edge of the roll paper passes the sensor 93 (timing t2 in the same figure).

[0044] Here, the control unit 110 detects the leading edge of the roll paper when it detects signal slope (K1) and signal slope (K2) consecutively within a predetermined set time (T1) (T1 = [circumferential distance from roller 92 to sensor 93 (mm)] ÷ paper leading edge linear velocity (mm / s) + margin), thereby suppressing false detections due to irregularities on the surface of the roll paper. Figures 9 and 10 show an example of a predetermined set time (T1) and signal slopes (K1) and (K2). Furthermore, the control unit 110 can improve detection accuracy by repeatedly performing the above detection operation if the leading edge is not detected during one rotation of the roll paper Pr, and by allowing the number of times the operation is performed to be set.

[0045] Furthermore, when two or more rollers 92 are arranged in the direction of the roll axis as shown in Figure 4, if the leading edge of the paper is cut at an angle, it may be difficult to detect the signal tilt (K1) of the sensor 93 when the leading edge of the roll paper passes through the roller. In such cases, the detection accuracy can be improved by repeating the signal tilt (K1) to signal tilt (K2) detection operation described above a predetermined number of times, and then detecting only the signal tilt (K2) when the leading edge of the roll paper passes through the sensor 93. Furthermore, when detecting the tip using only the signal tilt (K2), detection accuracy can be further improved by detecting the tip of the roll paper when the signal tilt (K2) is detected again within a certain time range (T2) corresponding to one rotation cycle of the roll paper after the first detection of the signal tilt (K2), and by allowing the number of detection operations to be arbitrarily set.

[0046] Referring to Figures 11 to 13, we will specifically explain examples of the operation of setting the roll paper Pr into the paper feeder 90 and examples of the operation of the leading edge detection process. The flowchart will use the following symbols for explanation. N: Number of times tip detection occurred M: Number of times the roll paper Pr was rotated K1: Sensor displacement output per unit time when the leading edge of the paper is removed from the roller. K2: Sensor displacement output per unit time when the leading edge of the paper leaves the paper thickness sensor. T1: After detection, this represents the range of the movement time of the roll tip from the roller to the sensor, calculated from the motor rotation speed and the distance from the roller to the sensor, plus the set margin. T2: After K1 detection, this represents the time after one rotation of the roll paper calculated from the motor speed + the range of the set margin. R: A value set to indicate how many times the roll paper will rotate before the tip is detected. a: This setting determines how many attempts are needed to identify the end of the paper roll. Use this setting if you want to increase reliability by performing multiple detections.

[0047] When the control unit 110 detects that the roll paper Pr has been set in the paper feed device 90, it controls the first motor drive unit 120 to make the roll paper rotating motor 131 rotate the roll paper Pr in reverse (CW) (S11) and start the leading edge detection process (S12). When the leading edge of the roll paper is detected, the control unit 110 instructs the first motor drive unit 120 to stop the roll paper rotating motor 131 so that the leading edge of the roll paper is in the paper leading edge stop position shown in Figure 4 (S13), makes the roll paper rotating motor 131 rotate the roll paper in forward (CCW) (S14), feeds the leading edge of the roll paper Pr in the paper feed transport direction (S15) and proceeds to the transport operation to the printing device.

[0048] As shown in Figure 11, after detecting the leading edge of the roll paper, the system continues to reverse, stopping the leading edge of the paper just before it passes the roller (the leading edge stopping position) as shown in Figure 6 (S13), and then transitioning to forward rotation (CCW) operation (S14).

[0049] Referring to FIG. 12, an operation example of the leading edge detection process (S12 in FIG. 11) will be described. In the leading edge detection process, the control unit 110 initializes parameters such as the number of times N that the leading edge has been detected, the number of times M that the roll paper Pr has been rotated, etc. (S21), increments the number of times M, rotates the roll paper Pr once, and detects the signal slope (K1) (S22). When the signal slope (K1) is detected (YES in S22), if the signal slope (K1) is detected within the time T1 (YES in S23), the number of times N is incremented (S24). When the number of times N is equal to or greater than the set value a (YES in S25), it is determined that the leading edge has been successfully detected (S26), and the process proceeds to step S13 in FIG. 11. Also, in step S25, when the number of times N is less than the set value a (NO in S25), after detecting the signal slope (K1), if the signal slope (K1) is detected again within the time T2 (YES in S27), and if the signal slope (K2) is detected within the time T1 after detecting the signal slope (K1) (YES in S28), the process returns to step S24.

[0050] On the other hand, when the signal slope (K1) is not detected (NO in S22), when the signal slope (K1) is not detected within the time T1 (NO in S23), when the signal slope (K1) is not detected again within the time T2 after detecting the signal slope (K1) (NO in S27), or when the signal slope (K2) is not detected within the time T1 after detecting the signal slope (K1) (NO in S28), if the number of times M that the roll paper Pr has been rotated is less than the number of times R (M < R) (NO in S29), the process returns to step S22. When the number of times M becomes equal to the number of times R (M ≥ R) (YES in S29), the leading edge re-detection process (S30) is executed.

[0051] Referring to FIG. 13, an operation example of the leading edge re-detection process (S13 in FIG. 12) will be described. In the leading edge re-detection process, the control unit 110 initializes parameters such as the number of times N of leading edge detection, the number of times M of rotating the roll paper Pr, etc. (S31), increments the number of times M, rotates the roll paper Pr once, and detects the signal slope (K2) (S32). When the signal slope (K2) is detected (YES in S32), the number of times N is incremented (S33). When the number of times N is equal to or greater than the set value a (YES in S34), it is determined that the leading edge detection is successful (S35), and the process proceeds to step S13 in FIG. 11. Also, in step S34, when the number of times N is less than the set value a (NO in S34), after detecting the signal slope (K2), if the signal slope (K2) is detected again within the time T2 (YES in S36), the process returns to step S33.

[0052] On the other hand, when the signal slope (K2) is not detected (NO in S32), or when the signal slope (K2) is not detected again within the time T2 after detecting the signal slope (K2) (NO in S36), if the number of times M of rotating the roll paper Pr is less than the number of times R (M < R) (NO in S37), the process returns to step S32. When the number of times M becomes equal to the number of times R (M ≥ R) (YES in S37), it is determined that the leading edge detection has failed, the roll paper rotation motor 131 is stopped, and the process ends (S38). At this time, it is advisable to notify the user of the occurrence of an error, such as by displaying an error message on an operation panel or the like.

[0053] Next, a mechanism for generating a peripheral speed difference between the roller and the roll paper in the paper feeding device of the present embodiment will be described. The mechanism for generating a peripheral speed difference between the roller and the roll paper separates the leading edge of the paper by creating a peripheral speed difference between the roller and the roll. At this time, the friction coefficient of the roller surface is set so that it is greater than the friction coefficient between the roll paper surfaces (the friction coefficient of the portion where the paper wound around the core Ps overlaps on the surface of the roll paper Pr). Also, the mechanism for generating a peripheral speed difference between the roller and the roll paper suppresses the peripheral speed of the roller when the roll paper Pr is rotated in the reverse direction (CW) and the leading edge of the paper is detected, and then when the roll paper is conveyed in the paper feeding direction (S13 in FIG. 11).

[0054] In this way, as shown in Figure 14, by slackening the paper and separating the leading edge of the roll paper from the surface of the roll paper, variations in the insertion position of the leading edge of the paper into the entrance guide plate 95 are suppressed, and it becomes possible to stably transport the paper downstream regardless of the paper condition (curl / paper type / paper thickness), thereby preventing jams due to poor separation. The following describes the details of the mechanism that creates a peripheral speed difference between the roller and the roll paper in each embodiment. In Figures 15 to 17, steps with the same numbers as in Figure 11 (S11 to S14) are the same processes and therefore their explanations are omitted as appropriate.

[0055] Embodiment 1. In this embodiment, one configuration in which the paper feeder 90 has a roller brake mechanism that suppresses (or stops) the peripheral speed of the roller 92 as a mechanism that creates a peripheral speed difference between the roller and the roll paper will be described. An example of the operation of this embodiment will be described with reference to Figure 15.

[0056] When the leading edge of the roll paper is detected (S12), the control unit 110 stops the roll paper rotation motor 131 so that the leading edge of the roll paper is in the paper leading edge stop position shown in Figure 4 (S13), activates the roller brake (ON) (S41), and then causes the roll paper rotation motor 131 to rotate the roll paper in the forward direction (CCW) (S14). After D seconds, the roller brake is stopped (S42), and the operation to transport the paper to the printing device is initiated. D is a preset value, which may be stored in a recording medium accessible to the control unit 110, or it may be stored within a program executed by the control unit 110.

[0057] According to the above example of operation, by stopping the leading edge of the paper just before it passes the roller as shown in Figure 6, and then switching on a brake connected to the roller (not shown) before transitioning to counterclockwise (CCW) rotation, it is possible to temporarily stop the roller 92, thereby creating a difference in rotational speed between the roller and the peripheral speed of the roll paper. This allows the paper to slacken and the leading edge to separate from the surface of the roll paper, as shown in Figure 14.

[0058] Embodiment 2. In this embodiment, one configuration in which a pressure release solenoid is used as a mechanism to create a peripheral speed difference between the roller and the roll paper in the paper feed device 90 is described. Figure 3 shows an example configuration in which a pressure release solenoid 98 is arranged. The pressure release solenoid 98 releases the pressure by rotating the arm 91 at its pivot point 911 in the opposite direction to the direction in which the arm 91 presses against the roll paper surface.

[0059] An example of operation of this embodiment will be described with reference to Figure 16. The control unit 110 performs tip detection processing (S12), activates the pressure release solenoid 98 after D seconds (S51), and then stops the roll paper rotating motor 131 (S13). Then, it starts the roll paper rotating motor 131 in forward rotation (S14), releases the pressure release solenoid 98 (S52), and proceeds to the transport operation to the printing device. D is a value set in advance, as in Embodiment 1.

[0060] As described above, this embodiment is characterized in that the arm 91 (support member) and the roller 92 are configured to be able to move away from the surface of the roll paper. Instead of attaching a brake mechanism to each receiving roller in Embodiment 1, the operation of the arm 91 contacting and retracting from the surface of the roll paper by a pressure release solenoid 98 is added. In this way, after detecting the leading edge of the roll paper, the pressure release solenoid 98 is turned ON, and the roller, together with the support member, is moved away from the surface of the roll paper while continuing to reverse. The paper leading edge is stopped just before it passes the roller as shown in Figure 6, and the machine transitions to forward rotation (CCW) operation while simultaneously turning OFF the pressure release solenoid 98. As a result, the roller 92 comes into contact with the surface of the roll paper again, and the friction coefficient between the roller surface and the roll paper surface due to the pressure of the roller 92 is greater than the friction coefficient between the roll paper surfaces themselves. Therefore, as in Embodiment 1, the paper can be loosened and the leading edge of the paper can be separated from the surface of the roll paper.

[0061] Embodiment 3. In this embodiment, one configuration in which a paper feeder 90 uses a one-way roller as a mechanism to create a peripheral speed difference between the roller and the roll paper is described. In this embodiment, the paper feeder 90 uses a one-way roller as the roller 92 and is equipped with a pressure release solenoid 98 as described in Embodiment 2.

[0062] An example of operation of this embodiment will be described with reference to Figure 17. The control unit 110 stops the roll paper rotating motor 131 (S13), then starts the roll paper rotating motor 131 in forward rotation, locks the one-way roller (S61), and feeds the leading edge of the roll paper Pr in the paper feed direction. Then, after D seconds, it operates the pressure release solenoid 98 (S62). D is a preset value, as in Embodiment 1.

[0063] As described above, this embodiment is characterized in that the roller 92 is a one-way roller that locks when the roll paper is rotating in the forward direction (paper feeding direction). Instead of attaching a brake mechanism to each receiving roller in Embodiment 1, the receiving rollers are made one-way. In this way, by making the roller a one-way roller that locks when the roll paper is rotating in the forward direction (paper feed direction), the leading edge of the paper is stopped just before it passes the roller as shown in Figure 6, and the roller locks simultaneously with the transition to forward rotation (CCW) operation. Then, due to the frictional resistance of the roller against the roll paper surface, as in the above embodiments, the paper is slackened and the leading edge of the paper is separated from the roll paper surface, and then by turning on the pressure release solenoid (S62), the roller is separated from the roll paper surface together with the support plate, and the paper can be transported downstream. This allows the device to rotate the roll paper in the direction that transports it into the device using a simple mechanism, and at the same time the rollers lock, causing the paper to slacken due to the frictional resistance of the rollers against the surface of the roll paper, separating the leading edge of the paper from the surface of the roll paper.

[0064] Other embodiments. Furthermore, two or more embodiments described above may be combined as appropriate. For example, a combination of Embodiment 1 and Embodiment 2, or a combination of Embodiment 2 and Embodiment 3 may be used. The paper feed device 90 may change the mechanism that creates a peripheral speed difference between the roller and the roll paper, for example, based on the type of paper.

[0065] As described above, one embodiment of the paper feeding device according to the present invention is It has a support member with a sensor and rollers placed in close proximity, The sensor and roller are positioned towards the approximate center of the roll of paper. The sensor and roller are configured to contact the surface of the roll paper. The sensor and roller are positioned offset from each other in the circumferential direction of the roll. The sensor has detection accuracy that allows it to detect the step (paper thickness) at the leading edge of the roll paper. The coefficient of friction between the roller surface and the roll paper surface is greater than the coefficient of friction between the roll paper surfaces themselves. In a device that detects the leading edge of a roll of paper by detecting the sensor output displacement per unit time of the sensor signal, the leading edge of the paper is separated by creating a difference in peripheral speed between the roller and the roll.

[0066] In this way, the aforementioned paper feeder can avoid a situation where the leading edge of the paper cannot be separated due to the curling of the paper or static electricity, thereby preventing paper feeding failures and transport problems such as paper jams. Furthermore, the above-mentioned paper feeding device can be implemented by adding simple components to the leading edge detection configuration, without using a dedicated pressing member, sheet member, etc., for separating the leading edge of the paper, as described in Patent Document 2, thus reducing costs. In addition, the aforementioned paper feeding device does not utilize static electricity generated by friction between the sheet and the pressing member for paper separation, making it possible to handle a variety of paper types. For example, it has the advantage of not requiring operations such as changing the pressing force settings of the sheet member and the pressing member depending on the type of paper.

[0067] It should be noted that the present invention is not limited to the embodiments shown above. Within the scope of the present invention, each element of the above embodiments can be changed, added, or modified in ways that would be easily conceivable to those skilled in the art. [Explanation of Symbols]

[0068] 6 Paper feed roller pair 80 Image forming apparatus 90 Paper feeder 91 Arm 92 Koro 93 Sensors 95 Entrance Guide Sign 98 Pressure release solenoid 110 Control Unit 120 First motor drive unit 130 Roll paper drive unit 131 Roll paper rotating motor 140 Second motor drive unit 150 Conveyor drive unit 160 Conveying section 170 Mechanism that creates a peripheral speed difference between the roller and the roll paper. [Prior art documents] [Patent Documents]

[0069] [Patent Document 1] Japanese Patent Publication No. 2021-113118 [Patent Document 2] Japanese Patent Publication No. 2011-225320

Claims

1. A paper feeder that supplies paper from a roll of paper in which a long sheet of paper is wound, A motor that rotates the spool on which the aforementioned roll of paper is wound, A sensor having detection accuracy capable of detecting a step at the leading edge of the paper on the surface of the roll paper, A roller positioned at a location different from the sensor in the circumferential direction of the roll paper, The sensor and the roller are positioned in close proximity, and a support member is provided that can support them so as to contact the surface of the roll paper. The sensor and the roller are arranged toward the core of the roll paper, A mechanism is provided to create a peripheral speed difference between the roller and the roll paper in order to separate the leading edge of the paper from the surface of the roll paper. The mechanism for generating the aforementioned peripheral speed difference is a paper feed device that, after detecting the leading edge of the paper and stopping the rotation of the motor, suppresses the peripheral speed of the roller while the roll paper and the roller are in contact, and then rotates the motor to transport the roll paper in the paper feeding direction, thereby generating the aforementioned peripheral speed difference.

2. The mechanism that generates the aforementioned peripheral speed difference is equipped with a braking mechanism that suppresses the peripheral speed of the roller. The paper feeding device according to feature 1.

3. A paper feeder that supplies paper from a roll of paper in which a long sheet of paper is wound, A motor that rotates the spool on which the aforementioned roll of paper is wound, A sensor having detection accuracy capable of detecting a step at the leading edge of the paper on the surface of the roll paper, A roller positioned at a location different from the sensor in the circumferential direction of the roll paper, The sensor and the roller are positioned in close proximity, and a support member is provided that can support them so as to contact the surface of the roll paper. The sensor and the roller are arranged toward the core of the roll paper, A mechanism is provided to create a peripheral speed difference between the roller and the roll paper in order to separate the leading edge of the paper from the surface of the roll paper. The mechanism for generating the peripheral speed difference is a paper feeder that detects the leading edge of the paper, separates the support member and the roller from the surface of the roll paper, stops the rotation of the motor, and then, after the motor has stopped, brings the support member and the roller into contact with the surface of the roll paper, thereby generating the peripheral speed difference.

4. A paper feeder that supplies paper from a roll of paper in which a long sheet of paper is wound, A motor that rotates the spool on which the aforementioned roll of paper is wound, A sensor having detection accuracy capable of detecting a step at the leading edge of the paper on the surface of the roll paper, A roller positioned at a location different from the sensor in the circumferential direction of the roll paper, The sensor and the roller are positioned in close proximity, and a support member is provided that can support them so as to contact the surface of the roll paper. The sensor and the roller are arranged toward the core of the roll paper, A mechanism is provided to create a peripheral speed difference between the roller and the roll paper in order to separate the leading edge of the paper from the surface of the roll paper. The roller is a one-way roller that locks when the roll paper is transported in the paper feed direction. The mechanism for generating the peripheral speed difference is a paper feed device that, after detecting the leading edge of the paper and stopping the rotation of the motor, locks the one-way roller when the motor restarts while the roll paper and the roller are in contact, thereby generating the peripheral speed difference.

5. An image forming apparatus comprising a paper feeding device according to any one of claims 1 to 4.

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